1. Field of the Invention
The present invention relates generally to an anodically generated porous alumina template, and more particularly to a thin-film based multilayer nanoporous template formed on a substrate for the subsequent creation of nanoscale materials.
2. Description of the Prior Art
Anodically generated nanoporous alumina has been widely studied on bulk aluminum substrates and used as a host template for the deposition of a wide variety of materials, see Martin, C. R., Nanomaterials: A membrane-based synthetic approach, Science, 1994, 266 (Dec. 23, 1994): pp. 1961-1965, the entire contents and disclosure of which is hereby incorporated by reference. The work by O'Sullivan and Wood in 1970, see O'Sullivan, J. P. and G. C. Wood, The morphology and mechanism of formation of porous anodic films on aluminum, Proceedings of the Royal Society of London, A., 1970, 317 (1970): pp. 511-543, the entire contents and disclosure of which is hereby incorporated by reference, experimentally examined the role of an applied electric field in steady state pore growth. They proposed that the electric field concentrated at the scalloped inner surfaces of the pore governed pore propagation as well as equilibrium dimensions of pore diameter and barrier layer thickness. This was the first realization that the porous alumina system is dynamic and that the governing parameter (ΔVapplied) may be manipulated to achieve the desired porous structure including the pore diameter and barrier layer characteristics. Although dynamic, the porous alumina system was still somewhat limited in application. However, the work of these pioneering researchers (O'Sullivan and Wood) was restricted to bulk aluminum metals and the oxidation/anodization of these bulk aluminum metals, which do not provide any means of eliminating the insulating oxide barrier layer and therefore have limited application for nanowire deposition.
Thus, there is a remaining need to provide a nanoporous, self-assembling, thin-film based template on a substrate with the ability to manipulate the oxide barrier layer in situ, thereby providing a conducting electrode surface at each pore base, with control of the resulting template thickness and pore diameter.